Device for producing sound



June 19,11934. l Q HR|5TEN50N 1,963,075

DEVICE FOR PRODUCING SOUND Filed May 14. 193?.

dm l/ ,M w 2f INVENTOR Oscar Chrtenon,

ATTORNEY Patented-June 19, 1934 UNITED STATES PATENT DFFICE 12 Claims.

This invention relates to a device for producing sound.

An object of the invention is the provision of a device for the reproduction of sound and which may be employed either as a receiver for telephones or for radios, in which a plate is employed formed of two sheets of thin metal having different co-efflcients of expansion, withthe sheets being secured together at a predetermined temperature so that when the plate is Icooled the sheets will be under a compressive and tensile stress, such a plate being subject to changes caused .by magneto-striction.

Another object of the invention is the provision of a sound-reproducing device based on the magnetostriction principle in which a plate is formed of two sheets of thin metal and secured together at a predetermined temperature so that when the plate is cooled the sheets ofY material will be under a compressive and tensile stress so that when a current is passed through a coil embracing the plate the acoustically modulated current is converted into sound energy by means of the magnetostrictive vibrations with the efciency of the device being increased by the compressivev stress and the polarizing i'leld on one of the sheets of metal.

A further object of the invention is the'provision of a sound reproducing device' in which 'a' plate is formed of a thin sheet of 'nickel secured, in any approved manner, to a thin metal plate having a co-eflcient of thermal expansion which is greater than vthe co-eiicient of expansion of the nickel so that the nickel is maintained under a permanent compressive stress which is utilized to increase the magnetostrictive eiect in the nickel when varying currents are passed through a coil embracing the plate for the purpose of producing sound waves.

This invention will be best understood from a consideration of the following detailed description, in View of the accompanying drawing forming a part of the specication; nevertheless,it is to be understood that the invention is not conned to the disclosure, being susceptible of such changes and modifications which shall deiine' no material departure from the salient features of the invention as expressed in the appended claims. In the drawing: f

Figure-1 is a view in perspective of a device co structed in accordance with the principles of my invention,

Figure2v is a transverse vertical section taken along the line 2-2 of Figure 3,

Figure 3 is a horizontal section taken along the line 3--3 of Figure 2,

Figure 4 is an enlarged fragmentary vertical section taken along the line 4 4 of Fig. 3, and

Figure 5 is an enlarged fragmentary vertical 60 section of the composite plate employed in the receiver,

Fig. 6 is a fragmentary vertical section taken at a right angle to the section shown in Fig. 2.

Referring more particularly to the drawing. 10 65 designates a base member formed of any well known insulating material and this is neatly tted within one end. of a cylinder 11 also formed of insulating material. y

'I'he outer end of the cylinder is provided with a 70 closure 12 which is concave and has a. central opening 13 for theemission of sound.

The cover 12 may be formed integrally with the cylinder 11 or may be n ade separately and connected thereto.

A pair of metal rings 14 and 15 are located concentrically uponr the base 10 and pole pieces 16 having inturned portions 17 are located between the rings 14 and 15. The rings and the pole pieces 16 through the inturned portions or anges 17 are s0 secured to the base member by means of screws 18. The rings 14 and 15 and likewise the poles 16 are formed of a metal which may be magnetized.

The rings 14 and 15 are of magnetic steel and are permanently magnetized across a diameter inline with the pole pieces 16 which are formed of soft iron so that the magnetic field extends between the two pole pieces for the purpose of establishing a polarizing iield on the nickel plate.

Disposed diametrically of the base member 10 is 90 a raised portion 20 formed integrally with the base member and, therefore, consists of insulating material. This raised portion forms a support for the unit, generally designated by the numeral 21.

A pair of bars 22 and 23 extend diametrically 95 of the base member 10 or the cylindrical member 11 and are connected together at their ends by means of bolts 24 having nuts 25,26 threaded on the projecting ends thereof. The inner portions of the bars 22 and 23 are cut away, as shown at 100 27, to provide a space for a purpose which will be presently explained. The cutting away from the central portion of the bars provides raised portions 28 at the ends of the bars which are in contact with each other in order to form the space between saidl bars.

A metal plate, shown in an enlarged view in Fig. 5, is formed of two thin sheets of metalsuch as zinc, indicated at 30, and a 4sheet formed of nickel, indicated at 31. 'I'hese plates have their no 'I'he nickel plate and zinc plateare tinned on one lside with solder and placedr together with their tinned surfaces in contact between steel v` plates which are in turn placed between the javaisl of a vice. The whole is then heated in any approved manner until the-solder on the surfaces of i moval from the vice.

gauge enamel insulated copper wire.

the plates is melted. The plates are then pressed tightly together and allowed to cool before re- Any metal, alloy, or material having a linear coefficient of expansion greater than that of nickel may be used to subject the nickel plate to permanent compressive stress andy among such metals and non-metals having the largest coefficients of expansion are zinc, aluminum, lead,

` tin and porcelain. Lead and tin, however, will not give good results because of their low melting points and low tensile strength. Porcelain may be used but due to the difculty of securing the nickel plate to the porcelain plate the porcelain is somewhat impractical for the purpose. It

Ahas been found, however, that aluminum and especially zinc give satisfactory results. A zinc plate soldered to the nickel plate with solder having a melting point of about 450 degrees Fr. will subject the nickel to a degree of compressive stress in which condition its susceptibility and magnetostrictive effect are greatest.

A thin shee't of insulating material, as shown at 40, isplaced upon the surface of the nickel but spaced therefrom a distance approximately a thirty-second of an inch. It will be appreciated that this distance may be varied, depending upon the size and the condition under which the plate is employed. The sheet 40 may be of any well known insulating material, but mica is preferable. This sheet is spaced from the nickel sheetby means of strips 41 located adjacent the. edgeof the sheet 40 and the metal plate 31B.

A second sheet of insulating material is shown at 42 and is located in fiat contact with the zinc surface of the plate 31a. This sheet may be lacquered and cemented to the outer face of the plate 31a.

0n the outer face of the sheet 40 is applied a thin piece of insulating material 44. The sheets 42 and 44 may be a strip of paper wrapped around ther-plate 31a and the insulating strip 40 and cemented in place.

A pair of coils of wire, shown at 45 and 46, embrace the opposite sides of the plate 31a are wound around said plate and are disposed upon opposite sides of the bars 22 and 23. These coils are provided in the form of winding of #44 B. 8: S. Both coils are wound in the same direction, each coil being simply a continuation of the other. In winding, the following procedure is employed:` The assembly is placed in the winding machine and the end of the wire from the spool supply is passed through an opening in one of the bars 22 or 23 and temporarily secured in place.- The wire is then wrapped around one section upon one side of the bars 22 and 23 until this section is secured. 'I'he assembly is then turned around in the winding machine so that it will revolve in the opposite direction. The end of the wire from the spool as shown at 48, to the bolt 24 by means of a nut 25. The other end of the winding is connected to the bolt 24a. A Wire 50 is connected to the bolt 24 by means of the nuts 25 and 26 While a wire 51 is connected in a similar manner to the bolt 24a. The wires 51 and 50 are the lead-in wires from the instrument. Y

As shown more particularly in Fig. 2 a flat strip 53 of `insulating material is located on each end of the plate 31a and has an elongated opening which neatly receives the ends of the plate 31a and the associated strips 41, 42, and 44. Thin bars or strips 43 are cemented to the projecting ends of the strips 42 and 44 at the opposite sides of the plate 31a for holding the strips 53 in place. The strips 42, 44, 53 and 43 are secured in position before the wire is Wound around the plate.

Tape 53fL formed of insulating material is wound around the exterior of the coils and cemented in position by a suitable lacquer.

A bolt 60.is threaded through the base member 10, the raised portion 20 and thelower bar 23 for holding the member 21 in position as a funit and slightly spaced above the magnetic ring 15.

The bar 22 is provided with a passage 61 which is adapted to align with the passage 13.

The nickel employed in the manufacture of the upper layer of the plate 31, as shown at 31, has been rened and annealed in vacuum, in hydrogen, or by other efficient method. It isto be noted that the removal of harmful impurities from the nickel and annealing it to the softest temper obtainable greatly increases the permeability and magnetostrictive effect and thereby the sensitivity of theV receiver. The receiver may be connected in the ordinary circuits and used for the same purpose as any other type of receiver and for best results it should be wound to match the impedance of the output or supply circuit.

In the present construction the nickel plate acts in place of a diaphragm and is actuated by magnetostrictive forces whichA generate vibrations in the plate proportional in amplitude or intensity to the receiver current variations. The electrical energy of the speech currents is converted into sound energy through magnetostrictive vibrations. It is probable that ldiaphragm resonance effects such a's are inherent in receivers' having mechanically vibrating diaphragms are absent in this receiverand that it therefore has more uniform'` frequency response characteristics.

If a thin nickel plate is placed within a helix traversed by a direct current the plate through the action of magnetostriction will contract in a direction parallel with the magnetic field, set up within the helix and expand in a direction perpendicular to the field. If the current passing through the coil were an acoustically modulated current, speech or musical' sounds it repret magnetic eld.

The alloy known as invar has the lsmallest coefficient of linear expansion of any metal or alloy known at the present time. Therefore, if a plate formed of invar is secured to a plate formed of any other` metal or alloy by the method described in the specification it will result in setting up a permanent tensile stress in the metal .or alloy. In actual `construction it has been found that by using nickel-iron alloys with invar a tensile stress is set up in the diaphragm. The degrees of tensile stress are controlled by the use of solders and brazng alloys of high and low melting points. Preferably thin platinite was used in setting up a sheet of invar. The longitudinal magnetostriction effect in platinitev is greater than in any other metal or alloy, although a diaphragm made from this combination is not quite as sensitive as diaphragms made from plate being formed of two sheets of metal havingdifferent co-eiiicients of expansion and secured together under such a temperature that one of the' sheets will be always under a compressive stress so that the last-mentioned sheet will be sensitive to an impressed magnetic field created when a current is passed through the coil, and means for connecting the ends of the coil with an output current.

2. A sound reproducing device comprising a housing having an opening irr one face, a permanent magnet fixed to an opposite face within said housing, apair of diametrically disposed spa/ced bars securedV to the last-mentioned face, a sound reproducing plate located between the bars formed of a pair of sheets of -metal having different co-efcients of expansion and secured together under such a temperature that when the plate is cooled one of the sheets will be under a compressive stress, a sheet of insulating material located -in contact with one face, a sheet of insulating material disposed at the opposite face of the plate and spaced therefrom, a coil of wire embracing the sheets of insulating material, in-

-sulating material enclosing the coil, means for connecting the ends of the coil with an output current. f

3. A sound reproducing device comprising a base, a permanent magnet fixed to said base, a pair of bars formed of insulating material and provided with a longitudinal slot therebetween, a plate located within the slot formed of a pair of sheets of metal having different co-eflicients of expansion and secured together .under such atemperature that when the plate is cooled one of the sheets will be under a'compressive stress, insulating material at opposite sides of the plate,

a coil of wire embracing the last-mentioned insulating material, and binding posts to which the ends of the coil are connected.

4. A-sound reproducing device comprising a base, a permanent magnet fixed to said base, a

i pair of bars formed of insulating material and provided with a longitudinal slot therebetween, a plate located within the slot formed of a pair of sheets of metal having different co-eicients /of expansion and secured together under such a temperature that when the plate is cooled one of the sheets will be under a compressive stress, insulating material at opposite sides of the plate, a coil of wire embracing the last-mentioned insulating material, binding posts to which the ends of the coil are connected-means for securing together the bars and for clamping the last-mentioned insulating material and plate rigidly in position.

` 5. A sound reproducing device comprising a base, a plate supported on the base, formed of a pair of sheets of. metal having different coefficients of expansion and secured together under such a temperature that when the plate is cooled one of the sheets will be under a compressive stress, insulating material at opposite faces of the plate, a coil of wire embracing the plate, the insulating material being located between the coil and the plate, means for connecting the ends of the coil withan output circuit, and means for creating a magnetic ilux in the neighborhood of the plate. p

6. A sound reproducing device comprising a base, a plate supported on the base, formed of a pair of sheets of metal having different coeiilcients of expansion and secured together under such a temperature that when the plate is cooled one of the sheets will be under a compressive stress, insulating material at opposite faces of the plate, a coil of wire embracing the plate, the insulating material being located between the coil andthe plate, means for connecting the ends of the coil With an output circuit, means for creating a magnetic flux in the neighborhood of the plate, bars for clamping the insulating material and platein position, portions of the coil being disposed upon opposite sides of the bars.

7. In a sound reproducing device, a plate formed of a magnetostrictive metal which is under a compressive stress directed along the plane of the plate, a coil of wire embracing the plate and adapted to have a current passed therethrough, and means for maintaining the plate in a magnetized state.

8. In a sound reproducing device, a plate formed of magnetostrictive metal which is under tensile stress, a coilr of Wire embracing the plate and adapted to have a current passed therethrough, and means for maintaining the plate in a magnetized state.

9. In a sound reproducing device, a plate formed of magnetostrictive metal which is under compressive stress directed along the plane of the plate, and a coil of Wire adjacent to the plate adapted to have a current passed therethrough, and means for maintaining the plate in a magnetized state.

l0. In a sound reproducing device, a plate formed of magnetostrictive metal which is under formed of a material having a coeii'cient of expansion which is different from' that of the first mentioned plate, means for securing the plates together at such a temperature that when they are cooled the iirst mentioned plate will be under permanent stress, a coil of wire embracing the composite plate and adapted t'o have a current passed therethrough, and means for maintaining the magnetic portion of the composite plate in a magnetized state.

12. In a sound reproducing device, a plate formed of magnetostrictive metal, a second 

